Scientists just created the world’s smallest thermometer — and it’s made from DNA.

Chemists at the University of Montreal manipulated DNA molecules to create the programmable temperature checkers, which are 20,000 times smaller than a human hair.

Their research, which was published Wednesday in the journal Nano Letters this week, will provide insight into how the body maintains the temperature of cells at a molecular level.

“We know that the temperature inside the human body is maintained at 37 degrees Celsius, but we have no idea whether there is a temperature variation at the nanoscale inside each individual cell,” one of the researchers, Alexis Vallée-Bélisle, said in a statement.

The Canadian researchers were able to expand on on a 60-year-old discovery that RNA, the chains of molecules in human bodies that transfers genetic code, can unfold when exposed to heat.

They were able to recreate that in DNA structures — using different temperatures to get the molecule to open and close.

As nanotechnology continues to get more popular, the scientists said their findings could eventually extend to electronic devices, where a similar mechanism may be able to prevent overheating.